The long term goal of this study is to evaluate the relationship among leptin, tumor necrosis factor alpha, insulin, and c-peptide with neonatal body composition, specifically neonatal fat mass. The secondary aim is to evaluate these factors as possible regulators and mechanisms relating to fetal intra-uterine growth. To evaluate the relationship between leptin, tumor necrosis factor alpha, insulin, and c-peptide and neonatal body composition, where we hypothesize cord leptin concentration has a significantly stronger correlation with fetal fat mass as compared with insulin, c-peptide, or tumor necrosis alpha. Furthermore, we hypothesize cord leptin has a stronger correlation with fat mass as compared with birth weight alone, and these correlations are stronger in infants of mothers with gestational diabetes mellitus as compared with infants of mothers with normal glucose tolerance. Our second specific aim is to determine if the placenta is a potential contributor to cord leptin and tumor necrosis factor alpha. We hypothesize that umbilical vein concentrations of leptin and tumor necrosis factor alpha are greater that those of the umbilical artery. We plan to test these hypotheses by collecting umbilical artery and vein cord blood from both infants of mothers with GDM and NGT and measuring the concentrations of leptin, tumor necrosis factor alpha, insulin, and c-peptide. Finally, leptin and tumor necrosis factor alpha will be obtained from the neonates at 48 hours of life to determine if fetal leptin amd tumor necrosis factor alpha production decreases following birth.